The present invention relates to a steam frothing device which can be attached to a steam outlet of a coffee machine or of a stand-alone steam producing device, to produce a product froth such as a milk froth. More particularly, the invention relates to an improved device which is capable of gently delivering the froth while maintaining its attributes and quality.
In order to generate frothed milk, a defined amount of air is usually sucked into the stream of milk and steam. Milk is usually sucked into a vacuum chamber by effect of venturi, as a result of a high velocity created by steam injected under pressure. Thus, pressurized steam serves as a vector to move milk and air through a restriction into an emulsifying chamber in which a thorough mixture of milk-steam-air is generated and milk is strongly emulsified to create a stable froth. Devices exist which can be plugged to a steam outlet of a coffee machine to deliver a milk froth according to this principle.
U.S. Pat. No. 6,499,389 B1 relates to a steam froth device of such kind. A nozzle arrangement is disclosed that is disposed downstream of a steam pipe and has a vacuum chamber, into which a milk supply line terminates. An air conduit connects to the milk supply line upstream of the vacuum chamber. An emulsifying chamber is disposed downstream of the vacuum chamber, with the emulsifying chamber having a chamber wall, a floor, a central flow-diverting protrusion and an outlet. The central, flow-diverting protrusion is embodied as a flow trap surrounding the outlet.